The continuing progress of living quality in recent years has resulted in increased industrial standards. The rise of environmental protection consciousness and the constitution of GMP Standards for food products and medicine manufacture, has resulted in an urgent demand for a mill to conform to various items of rigid GMP standards: a. ingredient; b. noise; c. percentage of metallic dust (chiefly sourced from the mill wheel wearing); d. temperature; and e. pollution. Nevertheless, none of the domestic manufacturers are able to produce a mill to pass the rigid GMP inspection.
A satisfactorily designed mill must consider five major factors: a. torsion; b. centrifugal force; c. destructive force; d. temperature; e. noise, and these five factors are all interrelated. When energy is transmitted by a motor or a transmission shaft to a mill, torsion is produced first and then centrifugal force is generated from torsion. Centrifugal force is transmitted to a mill wheel to thus form the necessary destructive force for milling by virtue of mill wheel gravity. At the moment the destructive force is produced, the problems such as the increase in temperature and noise come to pass simultaneously. The interrelation among all these factors is not negligible. However, the prior mill design uses a motor running at a fixed speed whereby input torsion is fixed and, accordingly, the destructive force is also fixed. The Raymond Ring-Roller Mill in accordance with prior art is such a type, for example. A mill of such type has to change its motor for increasing torsion in case of inadequate destructive force, or in consideration of a need for increasing production capacity. Nevertheless, unreasonable use and random increases of motor horsepower often results in squeezing milled materials into flakes, while excessive destructive force is more liable to cause increased wear of the mill wheel or machine, the increase of noise, the rise of temperature and crystal re-permutation of raw materials, which therefore causes a severe loss rather than an increase in productivity.
Though the devices in R.O.C. Patents 21011 (U.S. Pat. No. 3,955,766) and 24332 (U.S. Pat. No. 4,682,738) and 42355 have made some major improvements for grain milling (more than 13,000 meshes) and production capacity, they still fail to comply with GMP standards. Also, during the process of milling, the internal mill wheel will be pushed aside if it encounters a hard object. Upon overriding the obstacle, the internal mill wheel will soon hit the external mill which is the main cause for the mill wheels wearing.
In view of such problems as mill wheels wearing, unchangeable speed and failure of conform to GMP standard found in the prior arts and above-said mills, the inventor has devoted himself to delicate research together with related experience in machinery design and manufacture through persistent experiments and improvements, to successfully achieved the present invention.